In a rotary machine such as a turbo machine, an impeller which integrally rotates with a rotor is provided. The impeller includes a plurality of vanes and is accommodated in a casing.
In addition, a predetermined amount of clearance is required between the vanes and the casing to reliably prevent contact between the vanes of the impeller and the casing.
However, during operation of the rotary machine, synchronous vibrations due to a rotation frequency of the rotor, backlash of a bearing portion which supports the rotor, non-synchronous vibrations due to turbulence or the like of a flowing fluid, or the like may occur. Accordingly, the vanes oscillate beyond the clearance due to the vibrations and the vanes are likely to come into contact with the casing.
In view of the above, a state observation device disclosed in PTL 1 for observing a state of a turbo machine measures a rotation speed of a rotating body which is an impeller, shaft vibrations, and a tip clearance which is a gap between the rotating body and a casing by one senor which outputs a signal synchronized with a rotation of the rotating body, stores vibration amplitude, an amplification factor, and the tip clearance for each rotation speed during an initial operation, and weights the vibration amplitude, the amplification factor, and the tip clearance. In addition, in a case these sums exceed a preset threshold value, the state observation device determines that the state of the turbo machine is in an abnormal state and issues a warning.